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Open Loop Gain Ota

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20 Threads found on edaboard.com: Open Loop Gain Ota
First of all You have to understand how current mirrors works. Then, understood at least one high swing cascode CS and use them as load of your opamp. For this configuration 60dBs of open loop gain with shortest regular devices should be achievable (with 1GHz of GBW for this power and not too high load - sthing like a 1pF)
Offset appears at the output multiplied by the closed-loop gain. The open loop gain has little effect on that other than whatever effect it has on the closed-loop gain.
Check this site: It gives a thorough review how to test open loop gain gain without opening the loop.
You have already answered your own question. The main consideration is the error that you will see at the output when non-ideal circuits are used. This error has various components 1. Input common-mode variation 2. Input-referred offset 3. gain error, which is derived from feedback network accuracy and opamp open loop gain
I need some advice on how to measure open loop gain and phase of an amplifier. I am looking for a practical circuit to use in the lab rather than a Spice circuit. I have attached two circuits. The AVOL_Ideal-Servo is what I believe to be practical for a lab measurement. The reason I am using an ideal amplifier after the DUT is to (...)
Could you post a quick schematic maybe? Is the open loop gain of your amplifier alone allright?
Hi BillQ, at first, I don't think that common mode effects are responsible for your observation. The main point is, that in both cases (loop open/closed) the amplifier should have the same bias conditions. Secondly, it would be very helpful if you could tell us something about the type of your "amplifier" (opamp, ota, BJT, FET,...?) and (...)
Hello all, For the choise of the unity gain frequency of the gain boosting amplifiers we have the basic equation : β*funity,open loop,otagain boosterota Sorry, but I don't see any "equation".
Hi DenisMark, Have you ever simulated open-loop gain vs vod, AC loop gain @Vod=0 and AC loop gain @vod=vod,max which were described in EE240 project? How to add the stimulus? Best Regards.
Ok, let's put it straight and clear. You need the loop gain's phase margin, not the open loop gain phase response. Especially when your feedback factor is not 1, but 0.33, as you said. So, simulate the loop gain by appropriately breaking the loop and see (...)
Hi All, For Gm-ota-C integrator, I try to cancel dc offset since it's open loop and has very high gain. If I want to inject voltage or current to remove the offset, which position is better? The input path, output stage, or internal stage? Any comments would be appreciated. Any referrence will also be helpful.
hi everybody why capacitive loads are drived with nonbuffered opamp ie ota whereas opamps with buffer are used to drive resistive loads The main problem is the open loop gain. The open loop gain is some thing like this Av=gm * Ro, where gm is transconductance of the (...)
Just use an open loop high gain ota with a couple of inverters as the load.
Hi, as far as I know gm-C filter is an open-loop filter configuration, i.e. no DC feedback. Does this means that linearity become a problem for large input signal? The gain and cutoff freq itself is related to the accuracy of the gm of ota, how accurate can the gm be? Does the open loop DC (...)
i think constant Gm circuit are used in some kind of filters called Gm-filters, where the ota is used in open loop configuration and the value of Gm is important , not as in OPamp where we want just a high value cause the opamp gain will be considered by the feedback section, iabout the process u are talking very general u (...)
hello could you tell me what's happening. I design an ota for LDO and met this problem. When i do .OP and polarize inputs with a given voltage, everything is alright. I've got 100V/V gain and so on. How to set AC properly to achieve the same results? I simulate LDO with an open loop. negative input is grounded (...)
If you use resistor make a unit feedback, just be aware the open loop gain will be affected by the resistor if its value is not large enough use capacitance, be aware it will affect bandwidth and phase for it adds load to the output for the smrr and psrr, do not introduce the mismatch to the differential pair. check their definition
Hello I have to design a very high-speed fully-differential output comparator. If my design strategy is to use 2-stage open-loop millter ota, then do I have to use some kind of Common-mode Feedback Circuit for this type of comparator. I can design a track-latch comparator(which doesn't need above complexity) but my question is
i need design one SC circuit,the frequency of clock is 1MHZ,VDD=2.5V,the visual GND=1.25v.now i need to firm the ota spec.i want the open-loop gain of ota is 40db at 1mhz,and the PM is 45 degree at 0db. its right? the common inout voltage how to firm? and its should be ?
maybe offset error or ota has not enough open-loop gain